如何在REACTION js中使用上下文API管理全局状态 [英] How manage global state using context API in React js
本文介绍了如何在REACTION js中使用上下文API管理全局状态的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用useContext管理导航栏的状态时遇到问题。只要菜单切换，ATM My应用程序就会呈现菜单项。我希望此事件仅发生在onClick上，并且按钮不记录控制台日志消息，它只有在我直接单击链接项目例如：Home时才起作用。 所以我有两个问题。如何管理导航栏状态以显示如何隐藏菜单项，而不必为其创建新组件？ 我如何修复我的Click事件，因为它在菜单按钮本身或/和菜单项上触发？ 下面您将为App.js、Layout.js、ThemeConext.js、useTheme.js、useToggle.js、ToggleConext.js和使用切换上下文的导航栏编写代码片段。
我真的很希望在这里能得到一些帮助，伙计们，我是初级的，真的有点被困在这里了。 提前感谢你们所有人。Leo
App.js
//import { data } from '../../SkillData';
import Header from './Header';
import Navbar from './Navbar';
import Skills from './Skills';
import Layout from './Layout';
function App () {
return (
<Layout startingTheme="light" startingToggle={"show"}>
<div>
<Navbar />
<Header />
<Skills />
</div>
</Layout>
);
}
export default App;
Layout.js
import React, { useContext } from "react";
import { ThemeContext, ThemeProvider } from "../contexts/ThemeContext";
import { ToggleContext, ToggleProvider } from "../contexts/ToggleContext";
function Layout ({startingTheme, startingToggle, children}) {
return (
<>
<ThemeProvider startingTheme={startingTheme} >
<ToggleProvider startingToggle={startingToggle}>
<LayoutNoToggleProvider>
</LayoutNoToggleProvider>
</ToggleProvider>
<LayoutNoThemeProvider >{children}</LayoutNoThemeProvider>
</ThemeProvider>
</>
);
}
function LayoutNoToggleProvider ({children}) {
const toggle = useContext(ToggleContext);
return (
<div className={
toggle === false ? "navbar navbar-collapsed" : "navbar navbar-collapse show"
}>
{children}
</div>
)
}
function LayoutNoThemeProvider ({ children }) {
const {theme} = useContext(ThemeContext);
return (
<div className={
theme === "light" ?
"container-fluid bg-white" :
"container-fluid bg-dark"
}>
{children}
</div>
);
}
export default Layout;
ThemeContext
import React, { createContext} from "react";
import useTheme from "../hooks/useTheme";
export const ThemeContext = createContext();
function ThemeProvider ({children, startingTheme}) {
const { theme, setTheme } = useTheme(startingTheme);
return (
<ThemeContext.Provider value={
{theme, setTheme}
}>
{children}
</ThemeContext.Provider>
);
}
export { ThemeProvider };
useTheme.js
import { useState } from "react";
function useTheme (startingTheme ="light") {
const [theme, setTheme] = useState(startingTheme);
function validateTheme (themeValue) {
if (themeValue === "dark") {
setTheme("dark");
} else {
setTheme("light");
}
}
return {
theme,
setTheme: validateTheme,
}
}
export default useTheme;
ToggleConext.js
import React, { createContext } from "react";
import useToggle from "../hooks/useToggle";
export const ToggleContext = createContext();
function ToggleProvider({ children, startingToggle }) {
const { toggle, setToggle } = useToggle(startingToggle);
return (
<ToggleContext.Provider value={{ toggle, setToggle }}>
{children}
</ToggleContext.Provider>
);
}
export { ToggleProvider };
使用Toggle.js
import { useState } from "react";
function useToggle (startingToggle = false) {
const [toggle, setToggle] = useState(startingToggle);
function validateShowSidebar (showSidebarValue) {
if (showSidebarValue === "show") {
setToggle("show");
} else {
setToggle("");
}
}
return {
toggle,
setToggle: validateShowSidebar,
}
}
export default useToggle;
Navbar.js
import Image from "next/image";
import styles from "../../styles/Home.module.scss"
import Logo from "../../public/Knowledge Memo.svg"
import { useContext } from "react";
import { ThemeContext } from "../contexts/ThemeContext";
import { ToggleContext } from "../contexts/ToggleContext";
import Link from 'next/link';
import { useState } from "react";
const navbarData = [
{ id: "1",
title: "home",
ref: "#home"
},
{ id:"2",
title: "Skills",
ref: "#skills"
},
{ id:"3",
title: "The List",
ref: "#theList"
},
{ id: "4",
title: "Team",
ref: "#team"
},
{ id: "5",
title: "Contact",
ref: "#contact"
},
];
function Navbar() {
const theme = useContext(ThemeContext);
const toggle = useContext(ToggleContext);
return (
<>
<nav className={
theme === "light" ?
"navbar navbar-expand-lg navbar-dark fixed-top":
"navbar navbar-expand-lg navbar-dark bg-dark fixed-top id= mainNav"}>
<div className="container d-flex flex justify-content-between">
<a className="navbar-brand h-50" href="#page-top">
<div className="navbar-brand">
<Image
src={Logo}
alt="..."
fill="#fff"
objectFit="contain"
className="h-50"
/>
</div>
</a>
<button
onClick={ () => toggle === !toggle, console.log("clicked")}
className="navbar-toggler collapsed"
type="button"
data-bs-toggle="collapsed"
data-bs-target="#navbarResponsive"
aria-controls="navbarResponsive"
aria-expanded="false"
aria-label="Toggle navigation"
>
Menu
<i className="fa fa-bars ms-1 navbar-toggler" aria-hidden="true"></i>
</button>
{toggle ?
<div className="collapsed navbar-collapse mt-2 id=navbarResponsive">
<ul className="navbar-nav text-uppercase ms-auto py-4 py-lg-0">
{navbarData.map((link,idx) => {
return (
<li key={link.id}>
<Link href={`/${link.ref}`} className="nav-item" data-index={idx} passHref>
<a className="nav-link">
{link.title}
</a>
</Link>
</li>
);
})}
</ul>
</div>
: <div className="collapse navbar-collapse show mt-2 id=navbarResponsive">
<ul className="navbar-nav show text-uppercase ms-auto py-4 py-lg-0">
{navbarData.map((link,idx) => {
return (
<li key={link.id}>
<Link href={`/${link.ref}`} className="nav-item" data-index={idx} passHref>
<a className="nav-link">
{link.title}
</a>
</Link>
</li>
);
})}
</ul>
</div>}
</div>
</nav>
</>
);
}
export default Navbar;
推荐答案
您可以使用Reducer来尝试此实现，以便使用本地存储来处理状态更改。这不完全是您的实现，但您可以看到流程
在AppContext.jsx
combinedReducers将Reducer方法处理到给定状态组件
import { useReducer, createContext, useEffect } from "react";
import userReducer from "./reducers/userReducer";
import themeReducer from "./reducers/themeReducer";
export const APP_NAME = "test_app";
//Check the localstorage or set a default state
const initialState = JSON.parse(localStorage.getItem(APP_NAME))
? JSON.parse(localStorage.getItem(APP_NAME))
: {
user: {
username: "",
email: "",
isAdmin: false,
},
theme: { dark: false },
};
//Create your global context
const AppContext = createContext(initialState);
//Create combined reducers
const combinedReducers = ({ user, theme }, action) => ({
user: userReducer(user, action),
theme: themeReducer(theme, action),
});
const AppState = ({ children }) => {
//Making it to provider state
const [state, dispatch] = useReducer(combinedReducers, initialState);
useEffect(() => {
localStorage.setItem(APP_NAME, JSON.stringify(state));
}, [state]);
return (
<AppContext.Provider value={{ state, dispatch }}>
{children}
</AppContext.Provider>
);
};
export default AppState;
export { AppContext, AppState };
上述实现的工作原理与redux类似，但您需要将给定的状态结构化为特定的减法器以处理状态更改
react中的useEffect挂钩并将状态添加到依赖项数组中，以确保您的状态处于同步状态
在UserReducer.jsx
const userReducer = (state, action) => {
const { type, payload } = action;
switch (type) {
case "LOGIN":
return { ...state, ...payload };
case "LOGOUT":
return {};
default:
return state;
}
};
export default userReducer;
在ThemeReducer.jsx
const themeReducer = (state, action) => {
const { type, payload } = action;
switch (type) {
case "DARK":
return { ...payload };
default:
return state;
}
};
export default themeReducer;
在index.jsx中使用单个提供程序包装整个应用程序
import reactDom from "react-dom"
import React from "react"
import App from "./App"
import "./index.css"
import AppState from "./state/AppState"
reactDom.render(
<React.StrictMode>
<AppState >
<App />
</AppState>
</React.StrictMode>,
document.getElementById("root")
)
从App.jsx访问上下文
import { useContext } from "react";
import { AppContext } from "./state/AppState";
const App = () => {
const { state, dispatch } = useContext(AppContext);
const handleLogin = () => {
dispatch({
type: "LOGIN",
payload: {
username: "Mike",
email: "mike@gmail.com",
isAdmin: false,
},
});
};
const handleLogout = () => {
dispatch({
type: "LOGOUT",
payload: {},
});
};
return (
<div className="main-container">
<div className="container">
<p>Username: {state.user.username ? state.user.username : "Unknown"}</p>
<p>Email: {state.user.email ? state.user.email : "Unknown"}</p>
</div>
<button onClick={handleLogin}>Login</button>
<button onClick={handleLogout} style={{ background: "red" }}>
Login
</button>
</div>
);
};
export default App;
如果您想查看结构Github
，这里是我的代码链接这篇关于如何在REACTION js中使用上下文API管理全局状态的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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